The present application discloses a method and apparatus to ensure that harmful voltages will not be applied to a fixed wireless terminal (FWT) when it is connected to a premises land-line telephone-wiring. The fixed wireless terminal is disclosed in commonly-owned U.S. Pat. No. 4,658,096. Any voltage present in the land-line inter-telephone wiring of the premises telephone-installation not provided by the FWT is considered foreign, and must be prevented from being applied to the FWT.
In commonly owned U.S. Pat. No. 5,812,637, there is disclosed an apparatus for using the second land-line of the PSTN for coupling a plurality of telephones to either an FWT or a first landline, whereby the second land-line of a premises wiring may be used for providing connection to the FWT. Before coupling the FWT to the second land-line, a test must be performed to ensure that harmful foreign voltages are not present, which voltages are harmful to the FWT.
A fixed wireless terminal operating on a cellular or cellular-like network or radio network, provides an alternate method of connecting the premises"" (residence or business) telephone to the land-line telephone company""s central office. It replaces the usual, hardwired connection from the premises to the central office (CO). In cases where the telephone installation in the premises has been hardwired, and the FWT is to replace that connection, there is danger that the wire-connection to the land-line central office is still live. The voltages presentxe2x80x94especially when the CO tries to ring the telephonexe2x80x94are capable of causing significant damage to the FWT circuits. Conversely, when the FWT tries to ring the telephone by means of the premises wiring which is incorrectly still connected to the CO, the circuits at the CO may suffer damage.
In new installations, or remodeling efforts, it is also possible for workmen to accidentally connect a foreign voltage-source to the telephone wiring, such as the premises"" AC voltage supply, or low voltage AC for a lawn sprinkler system, and the like.
Alternatively, it may be desirable to connect the FWT to a premises"" second land-line, as disclosed in commonly owned U.S. Pat. No. 5,812,637, which discloses an apparatus for using the second land-line of the premises for coupling one or more extensions, so that each extension may use either the first line connected to the PSTN land-line or the second line connected to the FWT. Before coupling the FWT to the second land-line, a test must be performed to ensure that harmful foreign voltages are not present , which voltages are harmful to the FWT.
Current practice provides little or no protection. The wall-connection must be probed with a voltmeter or other general test equipment to ascertain the voltage, if any, present on the connector prior to connecting the FWT. Since test equipment is not normally available to the average premises"" keeper, the connection is not tested and the FWT telephone connector, such as an RJ-11 jack, is simply plugged in. In the event a foreign voltage is present, the tip/ring circuits of the FWT may sustain damage.
It is the primary objective of the present invention to provide a means for the FWT to sense the voltage present on the tip/ring connection, when the FWT is connected to the premises"" wiring. It, also, provides a means to disconnect the bulk of the FWT circuitry from the connection until the foreign-voltage measurement circuitry of the FWT declares the premises wiring-safe. These two means ensure a safe environment in which to establish the connection of the FWT to the premises wiring.
It is also the primary objective of the present invention to provide such a prevention means for use in directly connecting an FWT to a premises"" second land-line, whereby the present invention first senses that no foreign voltages are present on that second land-line, before the FWT is connected to the tip-and-ring lines of the premises"" second land-line.